The present invention relates to audio and visual presentations and, more particularly, to a method and apparatus for modifying and creating such presentations using “scratch” techniques and a MIDI interface.
For several years, disc jockeys (DJ's) have been creating an unusual form of musical presentation by placing their fingers on a record to control both the speed and direction of rotation of the record. Commonly, the DJ's rotate the record backward and forward in a quick repetitive motion to create the effect of a phrase being played forward and backward at a fast rate. This repetitive playing of short phrases in a musical presentation has come to be known as “scratching” and produces a distinctive tonal sound. Some musicians have adopted this mode of musical creation to introduce scratch phrases into original works. Scratching may also be accompanied by simultaneous changes in volume.
One issue with the common approach to creating this unusual musical effect is that the presentation is created by rapid motion of a playback needle in a groove of a vinyl record and the action of manually moving the record forward and backward rapidly to create the effect causes severe wear on both the record and the needle. Consequently, the life of both record and needle is significantly reduced. While cost attributable to having to replace the records and needles is one issue, the more significant issue is that vinyl records are being quickly replaced by audiotapes, compact disks and computer-stored songs. Further, today's major musical presentations are accompanied by video presentations of the artists playing the music and synchronization of the video with the DJ's scratching requires control of both the audio and video presentations.
In 1997 the European patent office published Patent Number WO9701168 (the '168 patent) for a Digital Processing Device for Audio Signal. That patent describes a system for the digital processing of audio signals, particularly for disc jockeys and scratch musicians. The speed and direction of reproduction of an audio signal coming from an external source, e.g., from a CD player, can be controlled by acting manually on a rotating element. The speed of rotation of this element is normally constant but can be modified by the disc jockey. The audio signal is sampled and stored at a constant frequency in a sampling buffer and read at a variable frequency as a function of the speed and direction of the rotating element. In one embodiment, the element is a record player turntable and the disc jockey can act upon the speed of rotation by using a hand to control the platter of the turntable. An optical sensor senses the speed and direction of rotation of the turntable and provides signals to control the speed and direction of reproduction of the sampled audio signal.
As best understood, the device of the '168 patent requires a system in which music obtained from an external source is stored in sequential data blocks in an addressable memory. The rotating element is a disk having a plurality of alternating white and black marks for generating a sequence of pulses as the disk is rotated beneath the optical sensor. Each pulse from the sensors causes the memory to step to a next one of the sequential data blocks, either forward or backward depending on the direction of rotation of the disk. In that manner, the DJ can control the speed and direction of playing of the music to create a scratch effect. The disadvantage of this device is that it requires a means of sequentially storing samples of music into a memory that can be addressed to cause the music samples to be played in sequential data blocks.
In about 1983, the music industry began developing a new form of communication protocol to allow electronic creation and control of music synthesis. The standard for this protocol was named Musical Instrument Digital Interface and became widely known as MIDI. Electronic instruments using this protocol became known as electronic synthesizers and can be found in the form of pianos, drums, organs and many other instruments. Using MIDI, multiple instruments can be coupled together to create a wide range of musical compositions.
One of the advantages of MIDI is that data is transmitted to an instrument in the form of a digital byte having a number of commands that tell the instrument when to start a note, when to stop the note, what frequency to play, what volume to play and what effects to give the note. Additionally, the data includes a time scale that allows the instrument to play at different tempos or beats per minute. For example, a composition that plays for four minutes at 80 beats per minute would only play for two minutes at 160 beats per minute. The MIDI protocol is constructed so that an external source can send timing data to a musical instrument to control tempo even for pre-recorded music being played by the instrument.
As computers have proliferated in the musical industry, various interfaces have been developed to allow computers to communicate with electronic musical instruments (synthesizers) and broaden the range of sound that can be generated. For example, the MIDI protocol requires that each byte of data specify a channel and the instrument will only respond to data related to that one channel. A computer can essentially simultaneously send out commands on multiple channels thereby controlling more instruments and more sounds at one time. Various software packages have been developed for creating music using this advantage of computers. Further, the music aspect of MIDI has been expanded to include audio-visual presentations so that images can be synchronized with audio in any presentation and at any tempo. What is now needed is an interface that allows a musician or a disk jockey to use the power of the MIDI protocol to create a new form of audio-visual presentation incorporating manual control of the presentation and manual musical interpretation using scratching.